Automatic drain valve



D. W, 1935. c. w. GORDON 2,924,574

AUTOMATIC DRAIN V VALVE Filed Jan. 15, 1934 INVENTOR CHARLES M gazaa/F/J 57 BY I QKZKM ATTORNEY Patented Dec. 17, 1935 PATENT OFFICEAUTOMATIC DRAIN VALVE Charles W. Gordon, Munster, Ind., assignor to The'Superheater Company, New York, N. Y.

Application January 15, 1934, Serial No. 706,614

8 Claims.

The present invention relates to superheaters and aims to provide anovel and efficient means for protecting superheaters from over-heating.

Many superheater installations at present are designed for final steamtemperatures approaching the safe limit of the metal of the tubes in thesuperheater so that variations in load and firing conditions notinfrequently cause the metal of such tubes to become overheated.Frequently,

the worst conditions to which the tubes of a superheater are exposedoccur in firing up the boiler, there being then no useful steam flowthru the superheater acting to cool the tubes. An insuflicient flow ofuseful cooling steam thru the superheater may occur also at other timesespecially when a large load is suddenly thrown off the boiler. Inaccordance with my invention, means are provided whereby steam ispermitted to escape through the superheater or superheat- 20 erswhenever the amount of steam going to the intended steam consumer orconsumers attached to the superheater or superheaters is below theamount needed at the time to prevent overheating of the tubes of thesuperheater.

25 The novel features of my invention are pointed out in the appendedclaims. In order, however, that the invention, together with its objectsand advantages, may be more fully and readily understood, I will nowdescribe in detail and in con- 30 nection with the accompanying drawingtwo superheater installations which are exemplifications of theinvention, selected from a number of possible embodiments thereof. Inthe drawing,

Fig. 1 is a vertical sectional view, diagrammatic 35 in character, of asuperheater boiler having my invention applied thereto. 7

Fig. 2 is a detail view, on an enlarged scale, of a portion of theapparatus illustrated diagrammatically in Fig. 1, parts being shown insection 40 and parts being broken away for purposes of i1- lustration. Q

Fig. 3 is a diagrammatic view similar in character to Fig. 1 butillustrating a different species of the invention. g

45 Fig. 4 is a view similar to Fig. 1 but illustrating a third speciesof the invention.

The apparatus illustrated in Figs. 1 and 2 comprises a boiler IQ ofknown type having a superheater 12 connected therewith, the heatingunits 50 I l of said superheater lying in the path of the heating gasesflowing through boiler l0. Su-

perheater l2 has a header It for saturated steam and a header l8' forsuperheated steam, header l6 being connected to boiler [0 by an inletcon- 55 duit 20. Steam from header it flows through the units I4 intoheader l8 and the superheated steam is conducted from header l8 to thepoint of use through an outlet pipe 22. Frequently boilers are installedin batteries and I have shown outlet pipe 22 connected to a steam main26 and 5 therefore have provided a non-return check valve 26 in the pipe22.

Steam flowing through the tubes it normally cools them to prevent theiroverheating, it being assumed that main 24 delivers to one or more 0steam consumers wln'ch normally place sufiicient load on boiler H) forthis purpose. Whenever, either during starting up periods or duringordinary running periods, conditions are such that overheating may beanticipated, the units M are protected in accordance, with my inventionby blowing off steam from header l8 either to waste or to some pointother than the normal steam users connected to main z l. Themeansillustrated for this purpose comprises a blow-off line having a pipe 28connected to the header i8 and a pipe 30 connected to discharge thesteam. Intermediate pipes 28 and 32 is a balanced valve 32 shown asimmediately adjacent the pipe 39. Valve 32 is biased to the openposition by a spring 3% arranged to act on the stem 35 of such valve.Valve 32 is shown as standing open. Intermediate the valve 32 and thepipe 28, the blow-off line branches, one branch 36 containing anadjustable restriction 38 therein and the other branch to containing asecond balanced valve 42 which is biased to the closed position by aspring M acting on the stem 85 of valve 42. The two branches 36 and #20extend between the points 46 and 48, point t3 being between valve 32 andvalve 42 so that a small amount of steam can flow through branch 36 andvalve 32 and so be discharged through pipe 30 without reference to theposition of valve 42.

Spring 34 holds valve 32 open, as shown, to permit such escape of steamuntil overpowered by means responsive to the flow of steam thru theunits I 4. Such means comprises a diaphragm 5% the lower face of whichis connected by pipe 52 to the inlet or saturated header it ofsuperheater I2. Thepressure in the header I 6 thus tends to close valve32 against spring 35. The upper face of diaphragm is, however, connectedto the pipe 28 or to header l8 by a pipe 54,

the pressure in header l8 therefore tending to 50 hold the valve 32open. When'there is a certain flow thru units l4, a suflicient pressuredinerence develops between headers l6 and i8 to overcome the spring 34and to close valve 32, header I8 having, thelower pressure during flowthru 55 ratus are so designed that valve 32 stands open unlesssuflicient steam is flowing to the load thru the superheater to protectit against being overheated by the furnace gases.

In line 36 and preferably at the point 46, I place a thermostat 56containing a volatile fluid the pressure of which is conducted by a pipe58 to a chamber beneath the diaphragm 60 which is so associated with thestem of valve 42 that pressure on the under side of diaphragm 60 tendsto open such valve. When the temperature of steam in the branch 36coming from the header I8 rises to a certain point, sufficient pressureis generated in the thermostat 56 to raise the valve 42 and permit aconsiderable flow of steam through the discharge pipe 30 of the blow-oilline. The amount of steam thus blown off is limited by the valve 32 tothat needed to protect the units I4 against overheating, an excessamount over that needed for such purpose being prevented by the factthat the'flow itself creates a pressure difference between headers I6and I8 which acts through pipes 52 and 54 on the diaphragm in thedirection tending to close the valve 32.

It will be seen that in the operation of the apparatus shown in Figs. 1and 2 the valve 42 will be opened, if valve 32 is open, at any time whenthe temperature of steam in outlet header I8 rises above a predeterminedpoint irrespective of whether this occurs during starting up periods orordinary running periods of the boiler or superheater. A quantity ofsteam which may be regulated and. predetermined by valve means 38 inbranch 36 flows throughsuch branch and valve 32 so long as valve 32 isopen, but such flow is quite small and the steam so escaping throughpipe 30 can be utilized in preheating feed water or in other ways sothat it is not entirely lost.

; Of course, whenever valve 32 is closed, there is not any-flow inbranch 36 and the steam surrounding thermostat 56 cools off permittingvalve 42 to close. 7

The arrangement illustrated in Fig. 3 is the same as that of Figs. 1 and2 except that the boiler IDA has baffling therein and that thethermostat 56A is exposed to the combustion gases of the boiler IOA,instead of to steam from the superheater. I do not limit myself to theuse of baffling, however. Whenever the gases are hot enough to endangerthe superheater, valve 42 is opened by thermostat 56A. If, at the time,insufficient steam is flowing thru the superheater to protect it, valve32 then opens and permits sulficient flow for this purpose.

In the drawing, the valve 42, which is biased to the closed position, isplaced closer to the header I8 than the valve 32 which is biased totheopen position. However, I do not limit myself to this and in thesystem illustrated in Fig.3 the relative position of valves 32 and 42 isentirely immaterial.

. The arrangement illustrated in Fig. 4 is the same as that illustratedin Fig.1, except that the thermostat 563, instead of lying in theby-pass or branch 36 is in the header I8 at the junction of pipe 28 withsuch header but arranged to contact with steam flowing thru the headerI8 to the normal steam users on line24 as well as with steam going thrupipe 28 and line 30.

It is permissible as to all forms of the invention illustrated that'valve 42 shall stand open when thermostats 56, 56A, and 56B havearrived at the temperature desired for theaverage working temperature ofthe superheated steam. The flow of steamthru the waste pipe 30 is thencontrolled r the superheater. Valve 32 and associated appaby valve 32.The spring 34 of such valve is set so that it permits valve 32 to closewhenever there is sufiicient flow thru the superheater to the nor-' malsteam users to protect it against overheating.

When such useful flow thru the superheater falls off to such a pointthat it affords insuflicient pro-- tection to the superheater, thespring 34 over-' comes the efiect of diaphragm 50 and opens the valve32. Such opening, however, due to the nature of springs, is almostexactly proportional to the amount by which such useful steam flow fallsbelow that required to protect the superheater, so that there is nounnecessary draft of steam from the boiler.

While the operationof'apparatuses illustrated will be apparent, to thoseskilled in the art from the foregoing description for purposes ofconvenience, I will now give a rsum of the operation of such apparatusesin certain situations occurring occurring commonly in use.

As to all three forms of apparatus illustrated: when the boiler is cold,valve 32 is open and valve 42 is closed.

As to the apparatus of Fig. 1: during starting up, Valve 32 is open andvalve 42 is closed at first but will open as soon as the steamtemperature reaches a predetermined point and stay open thereafter aslong as there is no load on the boiler due to the probable hightemperature of steam around the thermostat 56 whenever the boiler isbeing fired without load. During ordinary running conditions, valve 42of Fig. 1 will be closed due to the lowertemperature of the steamsurrounding thermostat 56, while valve 32 will also be closed, or nearlyso. Under emergency conditions, if the engine connected to the boiler ofFig. 1 suddenly drops its load, valve 32 immediately opens while valve42 opens soon after due to increase in temperature of the steamsurrounding thermostat 56. When the boiler of Fig. l is on dead bank,valve 42 is closed and valve 32 is open; when on floating bank, valve 32closes and valve 42 will remain closed.

As to the apparatus of Fig. 3: during firing up, valve '32 is open andvalve 42 is closed at first, out opens when the gases become hot. Duringnormal running conditions, valve 32 of Fig. 3 is closed and valve 42 isopen. If the engine connected to the boiler of Fig. 3 suddenly drops itsload in an emergency, valve 32 immediately opens while valve 42 isalready open, thereby affording immediate protective circulation. Whenthe fire is checked, valve 42 closes, while valve 32 remains open. Whenthe boiler of Fig. 3 is on dead bank, valve 42 is closed and valve 32 isopen; on floating bank, valve 32 is closed and valve 42 is open.

As to the apparatus illustrated in Fig. 4: during the starting upperiod, valve 42 is closed at first and valve 32 is open. Valve 42 alsoopens when the steam becomes hot. When the boiler of Fig. 4 is put onthe line, valve 32 closes due to the difference in pressure with anormal flow of steam, while valve 42 remains open. If the engineconnected to the boiler of Fig. 4 drops its load in an emergency, valve32 immediately opens, while valve 42' is already open. A fullyprotective circulation is at once established and is maintained untilthe fire is checked. When the fire has been checked, valve, 42 closeswhilevalve 32 remains open. If the boiler of Fig. 4 is put on dead bank,valve 42 closes while valve 32 remains open. If it is put on floatingbank, however, valve 32 closes while valve 42 will remain open. 7

Comparing the apparatus of Fig. lwith that of Fig. 4, the two systemsfunction in much the same manner, but it is preferred to design thethermostat for the system of Fig. 4 so that it will open valve 42 whenthe boiler is on the line, resulting in that the valve 42 is open duringthe first part of any emergency period. This is desirable rather thanotherwise, as it makes the system more sensitive and quicker action istherefore obtained when needed. After the fire is quenched, the actionof valve 42 is the same in both cases. During the bank period, theaction of both types is the same.

Comparing the apparatus of Fig. 3, in which the thermostat is in the gasspace, with the systems of Figs. 1 and 4, the action of the system ofFig. 3 differs from those of the other two figures mentioned in that theby-pass is eliminated and therefore no steam is wasted in the bankingcondition or during the starting up period, when the gases are too coldto damage the superheater.

While I have described and illustrated several arrangements which fallwithin my invention, I do not limit myself to such arrangements or toparticular details of the disclosure, it being understood that theappended claims are to be construed in their broad sense and withoutimportation of unnecessary limitations from other parts of thedisclosure In particular I do not limit myself in all cases to passingthe steam from the leak thru an automatic valve as it may go direct tothe atmosphere.

What I claim is:

1. The combination of a heater having an outlet pipe for deliveringfluid to an intended consumer thereof, a blow-off line connected toreceive fluid from the outlet side of said heater, a valve in said linebiased to closed position, automatic means for opening said valve topermit fluid to flow through said heater whenever the fluid temperaturein the heater rises to a certain point; and automatic valve means tolimit the flow through the'valve biased to closed position to preventwaste of steam.

2. The combination of a heater having an outlet pipe for deliveringfluid to an intended consumer thereof, a blow-01f line connected toreceive fluid from the outlet side of said heater, a valve in said linebiased to closed position, means providing a fluid leak from the outletside of said heater, a thermostat arranged to respond to the temperatureof the fluid flow caused by said leak, means controlled by saidthermostat for opening said valve at a prescribed upper temperaturelimit, and a second valve in series with the said first mentioned valve,such second valve being biased to the closed position, and automaticmeans for controlling the position of said second valve to preventwasting steam.

3. The combination with a heater having an outlet and an inlet of ablow-off line connected to said outlet and containing two automaticvalves in series, means whereby one of said valves is biased to the openposition, means whereby the other of said valves is biased to the closedposition, means including a thermostat for opening said other valve at aprescribed upper limit of steam temperature, and means for closing saidone valve whenever there is a predetermined steam flow thru the heater.

4. The combination as set forth in claim 3 and in which the means foropening the valve which is biased to the closed position includes aby-pass around such valve in which the thermostat is located.

5. The combination with a superheater having an outlet and an inlet of abloW-ofi line connected to said outlet and containing two automaticvalves in series, means whereby the one of said valves farther from saidoutlet is biased to the open position, means whereby the one of saidvalves nearer said outlet is biased to the closed position, meansincluding a thermostat for opening said valve nearer the outlet toprotect the superheater from excessive temperature, and means forclosing said farther valve whenever there is a predetermined steam flowthru the superheater.

6. The combination with a superheater having an outlet and an inlet of ablow-off line connected to said outlet and containing two automaticvalves in series, a spring arranged to bias one of said valves to theopen position, means arranged to bias the other of said valves to closedposition, means including a thermostat for opening said other valve toprotect the superheater from excessive temperature, and a diaphragmsubject to pressures from said inlet and outlet on opposite sidesthereof for closing said one valve whenever there is a predeterminedsteam flow thru the superheater.

7. The combination with a superheater having an outlet and an inlet of ablow-01f line connected to said outlet and containing two automaticvalves in series, means whereby one of said valves is biased to the openposition, means whereby the other of said valves is biased to the closedposition, means for closing said first valve whenever there is apredetermined steam flow thru the superheater, and means for openingsaid other valve to protect the superheater from excessive temperatureincluding a thermostat located in said outlet at the point of connectionthereto of said blow-oil line and so arranged as to be contacted bysteam in said outlet flowing either to said blow-01f line or to thenormal consumers of steam leaving the superheater.

8. The combination with a superheater having an outlet and an inlet of ablow-off line connected to said outlet and containing two automaticvalves in series, means whereby one of said valves is biased to the openposition, means whereby the other of said valves is biased to the closedposition, means for closing said first valve whenever there is apredetermined steam flow through the superheater, a boiler in which saidsuperheater is located, and means for opening said other valve toprotect the superheater from excessive temperature, and including athermostat located in the path of gases for heating said boiler.

CHARLES W. GORDON.

